It's hard to see a difference in arm quickness in the image above, but if you watch Betances pitch, you'll see that one of his biggest problems is repeating his delivery. As he points out in his quote, he can sometimes "drift", and it looks like this has an effect on his release point. When watching Betances throw, especially in his first outing this Spring, his arm slot looked like it had considerable range from around 10 O'Clock to 11 O'Clock.

In his more recent outing, his arm slot looked much more stable, and perhaps simplifying and repeating his arm motion has fixed that. Although it's only two appearances, on Febrauary 28th, Betances threw 1.0 innings where he walked two and hit one batter. He was visibly wild. On March 11th, he looked much more consistent with his release point, throwing 2.0 innings with 1 hit, no walks, and one hit by pitch.

When it comes to Betances' stride, it's very hard to tell a difference from the GIF above. I took a better video of his stride from 2011, and compared it to Chad Jennings' video of Betances working on his new mechanics.

Again, it's hard to tell, the difference can't be too drastic. When it comes to strides, many coaches dream on big guys with big strides pitching with high velocity. It means that the ball is leaving the hand of a pitcher that much closer to the batter, and it's something that can be devastating. Unfortunately, many of these pitchers take a long time to figure out how to control their mechanics, Randy Johnson being the example of success, and Andrew Brackman the example of failure. The big stride may have been a factor in his awful control.

Hopefully these changes can restore Betances' wildness. He still has great velocity, and his breaking pitches are strong. His baseball career now depends on his ability to control the ball. He'll turn 25 in a little over a week, and 2013 is likely a make or break season for the former top prospect.